1. Field of the Invention
The subject invention relates to a wheel and tire assembly for an automotive vehicle, and more particularly to an apparatus and method for mounting a valve stem into a wheel rim.
2. Description of the Prior Art
In the assembly of automotive wheel rims and tires, the tire is mounted onto the wheel rim and then inflated. Prior to mounting the tire, a valve stem is inserted into an aperture defined in the wheel rim to permit inflation of the tire. For manufacturing wheel rims on a large production scale, machines are used to automatically insert the valve stems into the wheel rims. Because the wheel rims of different sizes require differently sized valve stems, valve stemming machines must either operate on the wheel rims of a single size or be able to accommodate the use of several sizes of the valve stems.
Over the last few years, snap-in valve stems have become very popular in the automotive industry due to their ease of installation method. Clamp-in tire pressure monitoring systems type of a valve stem (the TPM) are similar to the snap-in valve stems, but also include a tire pressure monitor affixed to one end of the TPM. In order to install the TPM on the wheel rim, the TPM is placed through an opening defined in the wheel rim and then secured to the wheel rim by a retention nut over the TPM. A valve cap is then screwed onto the TPM to form an airtight seal and prevent dust and dirt from entering the valve.
Generally, as done in the past, mounting the valve stem into the wheel rim of any kind, have been performed manually. In particular, mounting the valve stem into the wheel rim has been performed by a stem-inserting tool. Such manual processes are expensive because of the labor and time involved. In addition, operations performed manually are subject to a processing error. Several prior art patents disclose processes for mounting the valve stem into the wheel rim. The art is also replete with various systems and methods, which involve a robot that installs the valve stem into the wheel rim. These systems are taught by the U.S. Pat. No. 4,353,156 to Rosaz; U.S. Pat. No. 5,940,960 to Doan et al.; U.S. Pat. No. 6,481,083 to Lawson et al.; and U.S. Pat. No. 6,801,126 to Harm. Other prior art devices utilize a rotatable carousel to dispense valve stems of varying sizes onto a valve stem insertion tool.
The U.S. Pat. No. 6,481,083 to Lawson et al., for example, teaches a valve stem assembly line that includes an input conveyor to supply wheel rim rims, a locator station positioned at the end of the input conveyor, a valve stem mounting station, adjacent the locator station, and an output conveyor for carrying the assembled wheel rim/stem units away. This prior art reference teaches a robotic manipulator to grasp the wheel rim in the locator station and to then move the wheel rim to three separate stem mounting stations each of which is loaded with a different type of valve stem, respectively. As each rim reaches the gauging station, video camera images the rim and the control system identifies it as either a car rim or a truck rim. The control system then directs the robotic manipulator to move the rim to whichever of the mounting stations is loaded with the correct stem for that rim. A nut runner mounted to the robotic manipulator is activated to thread a nut over the end of the valve stem only when a stem requiring such action, such as pressure transducer stem, has been mounted to the rim. The U.S. Pat. No. 6,481,083 to Lawson et al. teaches three separate stem mounting stations each loaded with a different type of valve stem intended for use with different types and/or sizes of wheel rims. The control system directs the robotic manipulator to move the wheel rim to one of the mounting stations.
The assembly line taught by the U.S. Pat. No. 6,481,083 to Lawson et al. is complex, bulky and requires three separate valve stem mounting stations with the robotic manipulator moving the wheel rim to the respective valve stem mounting station. This prior art system diminishes assembly time and flexibility of assembling environment. This system also performs numerous redundant operations, such as moving the wheel rim to different mounting stations which does not reduce time for assembly of the wheel rims and does not offer the flexibility needed in the modern manufacturing environment. Although the prior art valve stem installation systems are widely used in the automotive industry, these prior art designs have proven to be extremely complicated, and therefore non practicable, or have been inflexible in a manufacturing environment, particularly when a variety of valve stems are mated to a variety of the wheel rims.
The opportunity remains for a new design of the valve stem installation system for installation of at least two different valve stems into the wheel rim that will eliminate the need of an extra unit, reduce space in manufacturing environment, and offer the flexibility needed to process multiple sizes of tires.